An insertion device is a device which is used to insert a measuring instrument or sensor into a pipeline. More particularly, a pipeline sampling device or flow meter is best operated at an axially aligned position in a pipeline. When the device is at the centerline axis of the pipeline, more accurate measurements are made. Some devices are installed in the pipe at an eccentric position. Such devices need occasional cleaning. This is true both for flow meters and product sampling devices. Regarding insertion of such measuring instruments, they must be periodically retracted.
Retraction is required to enable pipeline pigs to pass along the pipeline. Otherwise, a full gauge pipeline pig will bend the mounting mechanism, perhaps destroying the measuring instrument and at least positioning it at the wrong location. Even worse, the pipeline pig may snag on the measuring instrument, blocking the pipeline against flow and creating an undesired pressure increase behind the pipeline pig. For these reasons, the insertion device must operate periodically to retract the measuring instrument so that a pig can traverse the pipeline without damaging the pipeline.
The normal insertion device involves a long piston rod. Typically, a piston placed in a hydraulic cylinder provides power to force the rod (which supports the measuring instrument) into the pipeline. Since pipeline pressure can be several hundred psi, even when the rod has a cross-sectional area of only one square inch, the opposing force can be substantial. With that representative dimension, it requires 1000 lbs. of force to overcome an ambient pipeline pressure of 1000 psi. Adding in the frictional engagement of the stuffing box, the force can easily be substantial to insert the rod into the pipeline. Moreover the piston rod normally in the cylinder is part of the rod. The cylinder may have substantial length. When the cylinder is long and the pipeline diameter is fairly large, the piston rod has to be quite long also. This rod is loaded with the compressive or axial load from the operation of the hydraulically powered piston. Loading of the rod at the pipeline is substantially equal and opposite in direction. Therefore the rod has a tendency to flex or bend. This can be countered by making a larger diameter rod. In turn, however, that increases the weight of the rod and further creates problems with heavier equipment. The present disclosure is a system which is much better than the end loaded, axially aligned hydraulic cylinders used heretofore. Representative devices known in the prior art are shown by patents of the present inventor which includes U.S. Pat. Nos. 4,177,676; 4,387,592; 4,346,611 and 4,631,967.
The present structure is an apparatus which provides an improved insertion device construction. More particularly, it is able to power the insertion rod without extending the height of the structure. So to speak, this invention provides a folded structure. The folded structure assures the positioning of the power cylinder parallel and adjacent to the insertion rod. Rather than being axially aligned, the insertion rod is adjacent to the insertion cylinder. This creates the risk of twisting when power is applied by the hydraulic cylinder to the insertion rod. Therefore two insertion cylinders are utilized, the two bracketing the insertion rod. So to speak, duplicate left and right hydraulic cylinders operated with a common power source and operated in a common fashion provide the power stroke. They connect with a transverse yoke member which is constructed so that the pulling forces of the two insertion cylinders are arranged symmetrically to the left and right, thereby balancing and assuring smooth insertion. Moreover, the two cylinders are positioned immediately adjacent to the valve mechanism which connects laterally from the pipeline so that the assembled apparatus including the insertion rod is reduced in height. This provides a much shorter structure which reduces overhead clearance problems.
The main insertion rod is inserted by a transverse yoke mechanism connected with two hydraulically powered cylinders. A lock down collar cooperative with the yoke mechanism enables adjustment so that the rod is fixed in position. This enables proper orientation of the insertion rod and equipment mounted at the remote extremity of it.
Consider representative dimension for the present system. It may be necessary to install a tee in a pipeline with a laterally directed passage extending to a blocking ball valve. The ball valve is constructed in a housing terminating in a pair of spaced, parallel flanges for easy mounting. A stuffing box is attached at one end of the ball valve and the opposite end of the ball valve is connected to the tee. The stuffing box supports the seals which enables the rod to be inserted through the stuffing box, through the ball valve, through the tee and ultimately to position a measuring apparatus at a centerline location within the pipeline. This is accomplished by mounting the measuring equipment on the axially moveable insertion rod. The rod is normally aligned with and serial extended by an upstanding hydraulic cylinder. Collectively, all of the above described equipment arranged in serially fashion typically requires a very high ceiling to shelter the apparatus in a suitable housing or other enclosure.
The hydraulic cylinder appended to the end of the insertion rod is not utilized in this novel arrangement. Rather, the entire structure is shortened. It is shortened so that the hydraulic cylinder is positioned to the side, reducing the height of the structure, and balancing the forces applied to the rod. This is accomplished by utilizing a single supply system cooperative with duplicate, double, acting hydraulic cylinders which are extended in parallel and retracted in parallel. Moreover, the parallel connected insertion and retraction system is capable of retracting by creating the properly sized force to insert the rod against the ambient pressure existing in the pipeline. One advantage of the present apparatus is that the total height of the structure is markedly reduced. Height reduction is achieved through a folded mechanism so that duplicate hydraulic cylinders are positioned parallel to and offset from the insertion rod, and are located so that the parallel hydraulic cylinders are on the left and right of the insertion rod. The insertion rod can be selectively locked in place. This is accomplished by incorporating a lock down collar on the rod which is anchored, thereby permitting locking against further axially movement of the insertion rod. Rotational movement is adjusted, and thereafter end by locking the insertion rod at a particular angular orientation.